ios - NSObject 在加载 viewDidLoad() 之前似乎没有初始化

Question

对新手问题表示歉意，但我真的很挣扎...我在尝试使用 NSObject 的自定义类创建 tableView 数据源时遇到问题。我已经设法在以前的 View Controller 中实现了这一点，但是当我尝试复制它时，它似乎不起作用。看起来 init() 函数不会在 tableview 上的 viewDidLoad() 之前完成，因此数据仅在显示表后添加到源中。

我能看到的唯一区别是 tableView 所在的 viewController 是 UITabBarController 的一部分...

这是当前代码...

EventTableViewController.swift

import UIKit
import Foundation

class EventTableViewController: UIViewController  {

    @IBOutlet var tableView: UITableView!

    var eventModel = EventModel()

    override func viewDidLoad() {
        super.viewDidLoad()

        // Do any additional setup after loading the view.
        tableView.dataSource = eventModel
        tableView.delegate = eventModel

        self.tableView.reloadData()
        print("Table already loaded")

    }
}

EventModel.swift

import Foundation
import UIKit

class Event {

    let eventName: String
    let eventType: String

    let eventStartDate: Date
    let eventEndDate: Date

    let participants: [String]

    init(item: PFObject) {
        self.eventName = (item["eventName"] as? String)!
        self.eventType = (item["eventType"] as? String)!
        self.eventStartDate = (item["startDate"] as? Date)!
        self.eventEndDate = (item["endDate"] as? Date)!
        self.participants = (item["eventParticipants"] as? [String])!
    }    
}

class EventModel: NSObject {

    var items = [Event]()

    override init() {
        // Setup the Events
        super.init()
        items = getAndConvertEvents()
    }


    func getAndConvertEvents() -> [Event] {

        var events = [Event]()
        let currentUser = PFUser.current()

        // Use this to get the events...!
        let query = PFQuery(className:"Events")
        query.whereKey("eventParticipants", contains: currentUser?.username)
        query.findObjectsInBackground { (objects: [PFObject]?, error: Error?) in
            if let error = error {
                // Log details of the failure
                print(error.localizedDescription)
            } else if let objects = objects {
                // The find succeeded.
                print("Successfully retrieved \(objects.count) events for user.")
                // Do something with the found objects
                for object in objects {
                    print(object.objectId as Any)
                }
                events = objects.map { Event.init(item: $0) }
            }
        }
        return events        
    }
}

extension EventModel: UITableViewDataSource {

    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
            return self.items.count
    }

    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        if let cell = tableView.dequeueReusableCell(withIdentifier: "EventTableViewCell", for: indexPath) as? EventTableViewCell {

            // Set the table parameters
            cell.nameLabel.text = items[indexPath.row].eventName

        }
        return UITableViewCell()
    }
}

extension EventModel: UITableViewDelegate {

    func tableView(_ tableView: UITableView, willSelectRowAt indexPath: IndexPath) -> IndexPath? {

        return indexPath
    }
}

有什么办法可以阻止 viewDidLoad() 在 EventModel 完成加载之前完成吗？

更新

我已经包含了我的 appdelegate 调用来初始化 UITabBarController

AppDelegate.swift

import UIKit
import Parse
import UserNotifications

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        // Override point for customization after application launch.
        let configuration = ParseClientConfiguration {
            $0.applicationId = ""
            $0.clientKey = ""
            $0.server = ""
            $0.isLocalDatastoreEnabled = true
        }
        Parse.initialize(with: configuration)

        let currentUser = PFUser.current()
        if currentUser != nil {
            // Do stuff with the user
            // Load the Event View as user is logged in
            let vc = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "EventTabController") as! UITabBarController
            self.window = UIWindow(frame: UIScreen.main.bounds)
            self.window?.rootViewController = vc
            self.window?.makeKeyAndVisible()

        } else {
            // Show the signup or login screen
            let mainStoryboard:UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
            let homePage = mainStoryboard.instantiateViewController(withIdentifier: "LoginView") as! StartVerificationViewController
            self.window?.rootViewController = homePage
        }


        return true
    }
}

Answer 1

@maddy 你是对的......!我在解析服务器调用中调用异步进程......!一如既往，我应该发布整个代码 - 抱歉，我什至不认为这会是问题!

我现在已更新为进行同步调用

    func getAndConvertEvents() -> [Event] {

            var events = [Event]()

            let currentUser = PFUser.current()

            // Use this to get the events...!
            let query = PFQuery(className:"Events")
            query.whereKey("eventParticipants", contains: currentUser?.username)
            do {
                let objects = try query.findObjects()
                print("Successfully retrieved \(objects.count) events for user.")
                // Do something with the found objects
                for object in objects {
                    print(object.objectId as Any)
                }
                events = objects.map { Event.init(item: $0) }
            } catch {
                    print(error.localizedDescription)
            }
            return events
        }